1. Field of the Invention
The invention concerns a cup grinding wheel including:                a cup-shaped carrier, and        an annular grinding body, wherein the grinding body is connected to the carrier by a single hot-pressing operation.        
The invention further seeks to provide a process for the production of the cup wheel according to the invention.
2. Description of the Related Art
Such cup wheels are already part of the state of the art and are shown, for example, in DE 25 48 28 1 C2 and DE 26 14 743 A1.
Cup grinding wheels are used for grinding metals like, for example, in tool grinding. These include, for example, machining processes like slot grinding, bevel grinding, finishing machining of boring tools and drills and tools, and so forth. A cup grinding wheel substantially comprises a carrier (grinding cup) and a grinding body of annular shape which at its surface has or provides grinding faces. The grinding faces are provided with super abrasive means like, for example, CBN or diamond which are bound together in a metal and/or synthetic resin binding.
There are several possible ways of producing a standard cup wheel, in which firstly the grinding body is produced, by the binding agent and the super abrasive means being introduced into a mold and then hot-pressed. After that hot-pressing operation, the annular grinding body is removed from the mold and put into a further mold. That further second mold is such that it predetermines the geometry of the carrier (grinding cup). The binding powder (binding agent) for the carrier, in the form of metal powder, synthetic resin, metal-synthetic resin mixture, etc., is introduced into that second mold and then hot-pressed. Two hot-pressing operations are required. The cup grinding wheel is finished after being removed from the mold. In the inside, the grinding cup has a supporting geometry in the region of the grinding body. That supporting geometry, often in the form of a ring, fixes and supports the grinding body on the carrier. That supporting ring must be set back to correspond to the wear of the grinding ring in a machining process (like, for example, by turning down in a turning lathe).
A disadvantage with that manufacturing process is that two hot-pressing operations have to be used. In addition, the grinding ring can be damaged upon being removed from the first mold. After removal from the first mold, sintering edges and contamination on the grinding ring have to be removed.
A further disadvantage which has nothing to do with the manufacturing process but with use of the wheel is that, upon the supporting edge being set back by a turning apparatus like a turning lathe, this involves time and work. In a further manufacturing variant, an independent supporting ring of plastic material is fitted behind the grinding body. In that case, the grinding body and the cup are produced separately from each other and then glued together. That is the case for example when, by virtue of its shape, the grinding body cannot be pushed over a ring which is shaped by the carrier. Subsequently, after the grinding body is glued to the grinding cup, the supporting ring is produced by molding a plastic material like, for example, epoxy resin, and an additional mold is required for that purpose.
That manufacturing variant also entails serious disadvantages: the grinding body and the grinding cup are produced separately from each other each in their own dedicated mold. Additional working steps like internal molding using an epoxy resin to provide the supporting ring and gluing the grinding body to the carrier in themselves constitute increased effort and complication. In addition, before the grinding body is glued to the carrier, a primer has to be applied to the adhesive surfaces in order to pre-treat them. Otherwise, it is not possible to ensure an adequate adhesive bond. Before the surfaces of the grinding body and the cup which are to be joined are glued together, they have to be pre-treated, for example, by sand blasting and degreasing with an agent like, for example, acetone and coated with a primer.